Paramedics, emergency care assistants, call handlers and other GMB members across the region walked out from midnight, with the action due to end at 11.59pm.
Workers voted to strike over the Government’s imposed four per cent pay award, which the unions say is another massive real terms pay cut.
Jacqueline Murphy, GMB rep at the picket lines in Donnington, Telford, said support remains strong among employees at West Midlands Ambulance Service.
"There are 12 of us out on the picket lines this morning and we have a fire going to keep us warm," she said.
"We are still angry with the Government over minimum cover. We are providing more than minimum cover, with staff leaving the picket lines to attend incidents and then coming back afterwards.
"They are trying to stop us striking by introducing a Bill they say is about minimum cover. It is spin from the Government trying to influence the public against us," she added.
And the mood on the picket line is still a determined one.
"We are standing up for the NHS," she said. "The public has been bringing us sausage rolls and they do recognise it is them who we are fighting for."
Ms Murphy added that support for the strike could dry up through "apathy" but the signs are that the public is behind them.
Ambulance chiefs have called on the public to use NHS 111 if they need medical help but to call 999 in an emergency.
Across the WMAS region, which includes Shropshire, there are major picket lines at Donnington, Shrewsbury, Dudley, Stoke and Hereford.
Simon Day, a union rep on the picket line at Shrewsbury ambulance station, said: "We have mixed feelings about being out again, including frustration that no real negotiations are taking place. They say they are negotiating but they are not.
"They say they want to talk about efficiency and productivity but it is difficult to be efficient and productive when you are stuck outside a hospital with a patient. The people who can pull the strings with that are not pulling any strings.
"We are elated with support from the public. There has been a drop in the number of 999 calls because people who can put up with their pain for a day have been doing so. That is humbling to us."
Service leaders still urge people to dial 999 if they are in a real emergency.
Stuart Richards, GMB senior organiser, said: “West Midlands ambulance workers’ message is clear - the Government must talk pay now.
“While the NHS crumbles around our ears – despite ambulance workers' desperate efforts – we have been waiting two weeks today for another meeting with ministers.
“Instead of working to solve the problems, this Government has demonised the ambulance workers who provided life and limb cover on strike days.
“The only way to solve this dispute is a proper pay offer. We are waiting.”